Thermal fluid–structural interaction of three cylinders undergoing flow-induced vibration with cross thermal buoyancy

Abstract

The effect of cross thermal buoyancy on the characteristic of flow-induced vibration and mixed convection of three circular cylinders is numerically studied. Two-dimensional simulations were conducted for a Reynolds number ( Re) of 100 and five Richardson numbers ( Ri) of 0–1.00. The range of the reduced velocity is 3 ≤ U* ≤ 15. Three circular cylinders C1, C2, and C3 are arranged in an equilateral triangle with C1 in upstream. The results show that the maximum amplitude of the C1 increases by up to 21% with considering cross thermal buoyancy in comparison to the case of Ri =  0. The galloping-like response is observed on the C1 at Ri =  1.00. The lift coefficient of three circular cylinders increases with the increase in Ri at U* ≥ 6. When U* exceeds a critical value, the vibrations of the C2 and C3 are in-phase, and the “2S” pattern is observed in the near-wake of three circular cylinders. The near-wake becomes wider, and the vortex shedding frequency increases at U* = 6 and Ri =  0.25 and 0.50. The higher the reduced velocity, the more significant is the effect of cross thermal buoyancy in enhancing heat transfer. The maximum space time-averaged Nusselt number increases by 10.42% in comparison to the case of fixed cylinders.